Atlas: Not 2x2 grid in subscription?

I'm confused. I thought a base subscription on the Xbox server (Steam crossplay) were to include a grid of 2x2 regions, but I only have 1 region to play on. I did choose an official 15x15 map, and chose H5 as my home region, but I thought I'd at least be able to sail to 3 adjacent regions. Is it because I chose this map and didn't go with the ordinary one? Or does a subscription only include 1 region?

So if I want another region I'll have to extend the subscription with another $10+ a month? And then another $10+ a month for yet another grid? Is that how this works?

Edit: Also, does the original nitrado region (the one we get if we don't install another map, like the 11x11 or 5x15 ones) include different biomes in the same region?

Okey!

I've already paid for 65 days (left) and if I add an expansion for $10+, will I lose access to the expanded area after 30 days, even if I still have 35 days left on base server?